In 2001 we brought two immigrants to America: orphaned Romanian teenagers. My framing of that event now is only slightly different from my moral thinking then. I reasoned that my own family, and to a lesser extent our circle of friends, were absorbing nearly all the inconvenience and cost. The question of assimilation became unimportant, because adoptees are among the most enculturated to mainstream society. As far as I could tell from the information given, I was not asking my local school district, nor America in general, to absorb expensive special-needs services that might have gone to some current resident. In fact, we actively avoided public school services they were eligible for, and sent them to a private Christian school. No ESL for them.
(In other places, BTW, Christian schools developed a reputation as white-flight academies, and perhaps that is/was justified. But up in NH, Christian schools had more diversity, not less, making significant efforts to bring in exchange students and treating disabled students well. There is a level of disability they cannot deal with, so the comparison may not be fair. But if you had a kid with some physical disability in that era, or a strange or eccentric child, you would find that kids in public school would torment him, kids in Christian schools encourage him. That's not theory, that's kids we knew. And in the case of our own, we wanted the greater emotional support they would receive.)
Yet we knew of situations from the same orphanage where children were brought to America who did turn out to require expensive special services. It was legal to bring them, and it was certainly kindly meant by the parents, but I am less certain of its pure generosity now. It is being generous with other people's money. I suppose the fact that it had been duly enacted in legislation and policy is proof that at some level, our society has signed on to that risk, but it is less obviously good than I once thought.
In our case it seems to have worked out as a plus for the country. One boy is a hospital accountant in Nome, which turns out in practical experience to be "a job Americans won't do." They have a hard time finding people to hire there, and a harder time finding ones who will actually show up and try hard. And yet...he went to a college down south for a year and a half, and at some level, took an admissions spot that might have gone...or maybe not. Hard to say. The second boy went into the USMC, which we traditionally regard as giving something important to the country. We may overrate that, as America did spend a million dollars training him which it did not recoup in combat or even supportive roles. He was ready, but never sent. Also, one can imagine that there is some native-born American whose enlistment slot he took, but really, it was only a delay of 30 days for a determined volunteer, and if the next person in line wasn't that determined, I don't feel too bad for him. That son now works in Norway, so the computation gets muddled.
Neither of them looks to turn out to be an axe murderer or a grasshopper refusing to work and sponging off others. But I suppose it could have happened, and I know I thought only a little at the time of what an unfair thing that would have been to do to my society, to unleash some monster on it. However well-meant I might be, it was still being generous with a little bit of other people's stuff. I didn't see it at all as potentially taking a job from some poor American. Had the economy been worse when we started the process in 2000, I might have. Since then I have come to question whether there will be meaningful paid employment for 50% of the population in 30 years. I had put my energy into making sure my descendants were in that 50%, or even, ultimately the 10% who actually do things rather than the 90% tricked into thinking they are important. Potentially, the boys I brought in might not have been taking jobs from my sector in America, but from poor Americans. I might have been being generous with things that were not mine, asking fellow-citizens to pay a cost I was evading.
And that's with a fully legal situation where someone has stepped up to pay most of the initial cost, and assimilation is largely guaranteed.
At an even more worrisome level, sponsoring agencies bring in immigrants, all quite legally, and agree to look after them and launch them and provide services for them for 6 months, or 18 months, or two years. They set that limit in order to push people out of the nest to make it on their own - mostly a good thing - but also to be able to devote their energy to others coming in.
Some of those pushed out of the nest don't fly. I get to see some of those, and I have some resentment at the agencies, some of them church-based, who take this approach. That they are sticking others with the later costs is more visible to me than to others. They see themselves as generous Christians, expressing the love of Christ to the unfortunate - and that's not necessarily untrue. But they are being generous with other people's stuff as well as their own. And even if that were not the case, that's not quite what Jesus (and Paul) said anyway. There's a standard modern sheep vs. goats misreading buried in there as well.
I mention this because these are the legal situations - the one the society has at some level agreed to be generous, or at least risk being generous about. With the unsponsored the risk becomes greater, and with illegals even more. I say this primarily for Christians who have fallen unthinkingly into the idea that this is all generosity, something we should righteously encourage our government to do more of, and encourage lawbreaking when it doesn't. Even the very best situations involve some giving away of other people's stuff. A job, some school funding, a place at a university. It's not really generosity. Someone is being generous, of course, but mostly it's not us. It's the poor, the less skilled, the (gulp) disabled, the unattractive, the uncharming, and above all, minorities who are paying that price.
We might decide as a society that we want to bring in certain non-citizens because the citizens who don't work have ticked us off, or to pressure them, or improve our own economy, or to maintain our Welcoming status at the expense of some who live here. We could decide that and even justify it. What I am calling into question here is the idea that doing so is obviously moral and generous, and opposing such things automatically stingy and bigoted.